One type of material handling unit that has found a remarkable degree of commercial success is what is commonly referred to as a loader backhoe unit. A loader backhoe unit consists of a vehicle that includes a chassis frame and pneumatic tires which support the chassis frame. The chassis frame has a backhoe unit supported on the rear end thereof and a loader unit on the forward end. The backhoe unit on the rear end generally consists of a boom having a dipper stick assembly pivotally supported on the outer end thereof with a bucket pivoted on the outer end of the dipper stick assembly. Normally, the boom and dipper stick assembly are of substantial length so that the bucket can be moved a substantial distance from the rear end of the vehicle.
The loader unit on the forward end of the vehicle generally consists of a pair of elongated lift arms that are pivotally supported on opposite sides of the chassis frame intermediate the opposite ends thereof with the forward ends of arms extending forwardly beyond the chassis frame and a bucket pivotally supported on the outer ends of the lift arms.
Generally this type of vehicle also includes stabilizing means adjacent the rear end of the vehicle for raising the rear or driving wheels off the ground during the use of the vehicle as a backhoe unit. These generally consist of a pair of stabilizer arms respectively pivotally supported on the rear end of the chassis frame and moved from retracted to extended positions by fluid rams.
These vehicles are generally operated in extremely rough terrain and as such, it has become customary to support the front wheels on an axle which is pivoted about a longitudinal pivot axis on the center of the forward end of the chassis frame. Such an arrangement has resulted in substantially reducing the stability of the vehicle, particularly when the vehicle backhoe unit is being operated. Thus, in order to increase the stability of the unit during the backhoe operation, operators generally lower the loader bucket to engage the ground and many times will utilize the loader bucket and pivot arms to raise the front wheels off the ground. However, such an arrangement has been found to be less than totally satisfactory for several reasons. Utilizing the front end mounted bucket loader as a stabilizer induces stresses into the loader arm causing premature failure. In addition, as indicated above, the operation of the unit is normally done in extremely uneven terrain and the bucket, which is usually at least equal to the width of the vehicle, has no means to compensate for such uneven terrain or ground conditions.